The downwind turn.

[skyking]

Please go back and read my explanation. The plane is in air, and could give two craps about direction WRT the earth. there is no acceleration going on here.
It is at 90 mph IAS, and is still at 90 mph IAS at every instant of the manuever, given the conditions of "The pilot does a 180 degree turn at constant altitude in 30 seconds."
The speed over the ground is not important.

 

[KillerCharlie]

Then you just answered your own question... it's always at 90 mph IAS and the stall speed is 50 mph IAS, so it wouldn't stall...

 

[skyking]

It was not my question, charlie🙂

 

[drinkmorejava]

Um, yeah, it stays in the air, pretty dumb question. If someone really wanted to, they could calc the centripetal acceleration to determine the exit velocity of the turn, but I can guarantee you that it's going to be more than 20mph.

 

[FoBoT]

skyking answered the question. the OP needs to declare skyking the winner and award him his

 

[skyking]

Damn, I'm getting hungry........😛

 

[JDrake]

No

 

[archiloco]

i voted yes, cuz i thought it was a trick question.

 

[Armitage]

Yep, skyking has the first correct answer - here's your

 

[thirdlegstump]

Not very likely although an aircraft can stall at any speed, it all depends on the attitude or aoa. 30 knt headwind at 60knt groundspeed is 90knt airspeed, well above the normal stall speed. As long as pilot follows relatively safe turning procedure, it won't stall and will maintain safe airspeed. Once he makes that turn and maintains the same airspeed, he'll be doing 120knts groundspeed..I think.

Conveyor belt not a factor here : )

 

[Armitage]

Originally posted by: KillerCharlie
So let me get this straight:

Airplane's ground speed is initially 60mph and a 30 mph headwind (it's flying into a wind that is 30mph wrt to the ground). That makes the IAS (plane speed wrt to the freestream - the "relative wind" as its known by pilots) 90 mph.

The aircraft then atempts a 180 degree turn while holding the altitude constant, but the aircraft cannot accelerate fast enough to gain 20mph. 20mph what - ground speed or IAS? That makes a difference.

Nope - makes no difference at all because the aircraft doesn't have to accelerate at all to maintain its 90 mph indicated.

You're saying that the engine can't provide enough acceleration, so you're pretty much saying it's going to stall. In real life the engine (held at a fixed setting) would probably accelerate you fast enough so that your IAS is above stall speed once you've turned.

Also, a quick note: stall depends only on angle of attack, not airspeed. When a stall speed is given, that's the speed the aircraft would stall at trying to fly straight and level at a certain weight. If you increase your weight above this reference value, your aircraft will stall at a higher airspeed.

 

[91TTZ]

The ground speed has nothing to do with it, other than to figure out what the airspeed is in the beginning of the problem.

The airspeed is 90 mph. Forget about the ground. After the turn, the airspeed is 90 mph. So no, it won't stall.